There is a general need for materials with low dielectric constants (low-k) in the integrated circuit manufacturing industry. Using low-k materials as the interlayer dielectric of conductive interconnects reduces the delay in signal propagation and signal crosstalk due to capacitive effects. The lower the dielectric constant of the dielectric, the lower the capacitance of the dielectric and the RC delay in the lines and signal crosstalk between electrical lines of the IC. Further, the use of low k materials as interlayer dielectrics will reduce power consumption of complex integrated circuits.
Low-k dielectrics are conventionally defined as those materials that have a dielectric constant (k) lower than that of silicon dioxide (SiO2), that is k<˜4. Generally, they have a dielectric constant of 3 or less. Typical methods of obtaining low-k materials include introducing pores into the dielectric matrix and/or doping silicon dioxide with various hydrocarbons or fluorine. In technology nodes of 90 nanometers and beyond (e.g., 65 nanometers), carbon doped oxide dielectric materials look extremely promising. However, wide spread deployment of these materials in modern integrated circuit fabrication processes is hindered by increasing demands for high mechanical strength coupled with lower dielectric constants. For certain applications, it is now necessary to use dielectric materials having k values below about 2.7.